Preheat the oven to 180 °C. Beat the icing sugar, vanilla-infused sugar, salt and egg until frothy. Slowing stir in the baking oil until you achieve a mayonnaise consistency. Then fold in the flour and hazelnut or walnut brittle.
Pour the mixture into a piping bag bag with a large spout and pipe small mounds onto a baking tray lined with baking paper. Bake the biscuits in a preheated oven for around 12 minutes until lightly coloured.
To finish, stick two mounds together with raspberry jam to form a ball and dust the biscuits with icing sugar.